The primary objective is to assess the effect of corticosteroid therapy in sarcoidosis. The pathologic process and the associated physiological impairment of lung function or other organ function are improved by corticosteroid therapy by short-term observations. It is not established whether these immediate beneficial results exert the same and prevents residual continued impairment of function. The design of the study is double-blind using steroid and placebo as therapy. Clinical and physiological studies are made at intervals and a final assessment made at five years. Additional areas of study are made from the available clinical material and include the incidence and diagnostic value of serum levels of converting enzyme for angiotensin, the population of T cells in sarcoidosis and tissue typing for the prevelance associated with sarcoidosis. Exercise studies are made for use in assessing diability and as a further method of classification of sarcoidosis. BIBLIOGRAPHIC REFERENCES: Gourin, A., Rosen, Y. and Lyons, H.A.: The Relative Value of Biopsy Sites in Diagnosis of Intrathoracic Sarcoidosis. Amer. Rev. Resp. Dis. 113:4, Part 2, 115, April, 1976. Silverstein, E., Friedland, J., Lyons, H.A., and Gourin, A.: Markedly Elevated Angiotensin Converting Enzyme in Lymph Nodes Containing Non-Necrotizing Granulomas in Sarcoidosis. Proceed., of the Nat'l Academy of Sciences, USA, 73, p. 2137-3141, 1976.